Oil, one of the sons of Kohath, and grandson of Levi (Ex. 6:18, 21; Num. 16:1).
Izhar
Izhar was a son of Kohath, and so a grandson of Levi, which makes him one of the founding names among the Levites. Exodus lists his brothers as Amram, Hebron and Uzziel, and gives Izhar’s own sons as “Korah, and Nepheg, and Zichri.” The same list is copied in Chronicles, where a later passage notes that Shelomith was chief among his sons. Most of what Scripture says of him is family record, which may feel dry. The name matters because Korah will later lead a rebellion against Moses, so the line that begins here ends in a hard story, found in Numbers 16.
7 verses
Exodus
Exodus 6:18
And the sons of Kohath; Amram, and Izhar, and Hebron, and Uzziel: and the years of the life of Kohath were an hundred thirty and three years.
Exodus 6:21
And the sons of Izhar; Korah, and Nepheg, and Zichri.
1 Chronicles
1 Chronicles 6:2
And the sons of Kohath; Amram, Izhar, and Hebron, and Uzziel.
1 Chronicles 6:18
And the sons of Kohath were, Amram, and Izhar, and Hebron, and Uzziel.
1 Chronicles 6:38
The son of Izhar, the son of Kohath, the son of Levi, the son of Israel.
1 Chronicles 23:12
The sons of Kohath; Amram, Izhar, Hebron, and Uzziel, four.
1 Chronicles 23:18
Of the sons of Izhar; Shelomith the chief.
From Easton's Bible Dictionary
Matthew George Easton, 1897
From Smith's Bible Dictionary
William Smith, 1884
(oil), son of Kohath grandson of Levi, uncle of Aaron and Moses and father of Korah. (Exodus 6:18,21; Numbers 3:19; 16:1; 1 Chronicles 6:2,18) (B.C. after 1490.) Izhar was the head of the family of the Izharites, (1 Chronicles 24:22; 26:23) or Izeharites. (Numbers 3:27; 1 Chronicles 26:23,29)